A METHOD OF PRODUCING BOTTLE OR TUBE-LIKE, CAPPED PACKAGING CONTAINERS FROM A POLYMER MATERIAL

Abstract: The disclosure relates to a method of producing bottle or tube-like, capped packages from a polymer material which is plastically formable in the heated state. In the forming operation, a sheet (7) of polymer material heated to plasticity is fixedly clamped over the aperture (2) of a conically shaped cavity (1) corresponding to the form and size of the produced packaging container. The plastic sheet (7) is pressed into the cavity (1) by means of a mandrel (9) at the same time as blades or vanes (10) supported by the mandrel (9) are folded out in the radial direction from the mandrel (9) and urge the plastic polymer material against the walls (3) of the cavity (1), the walls being provided with channels or slots which may be placed in communication with a vacuum source. The forward portion (11) of the mandrel (9) forces parts of the polymer material into a cap (5) disposed in the innermost region of the cavity (1), with which cap the polymer material can be united. Finally, the hollow body (4) formed from the polymer material is removed from the cavity (1), filled with its intended contents and sealed by means of a preformed bottom portion (12).

Description: A METHOD OF PRODUCING BOTTLE OR TUBE-LIKE, CAPPED PACKAGING CONTAINERS FROM A POLYMER MATERIAL TECHNICAL FIELD The present invention relates to a method of producing bottle or tube¬ like, capped packaging containers from a polymer material which is plastically formable in the heated state. BACKGROUND ART There is a need in the art to be able to produce bottle or tube-like packages which are formed from a deep-drawn or vacuum-formed hollow body which, already prior to filling, is fitted with a cap, for example a screw or snap-on cap, and which may be transported in an economical manner from the packaging manufacturer to the filler. It is previously known in the art to produce blown or vacuum-formed packaging containers which, in the blowing or vacuum-forming operation, are provided with threads adapted to fit separately manufactured caps. It is also known in the art to cover a hole made in a paperboard package with a thermoplastic film of a rigid plastic material and subsequently, after heating, to vacuum-draw this plastic film exposed in the hole up into a screw cap, the plastically formed plastic film then connecting with the inside of the cap so that a moulding of the threads in the cap occurs in the deep-drawn or vacuum-formed plastic film. OBJECT OF THE INVENTION However, the present need in the art (which constitutes the central object of the present invention) is to produce a complete bottle-like container, with a controlled wall thickness, by first producing mutually stackable or nestable hollow bodies or parisons which, on forming of the hollow bodies, are provided with a cap, and subsequently - after transport to a filler - progressively filling the separated hollow bodies with their intended contents and thereafter applying a suitable bottom portion with the aid of heat and pressure. SOLUTION The solution to this problem is to provide one or more deep-drawing cavities whose walls are provided with apertures or gaps through which the air within the cavity can be evacuated. The novel and characterizing features of the present invention will be apparent from the characterizing clauses of the appended Claims. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS One preferred embodiment of the present invention will now be described in greater detail hereinbelow, with particular reference to the accompanying schematic Drawings. In the accompanying Drawings: Figs. 1 A-D show how production of a hollow body takes place; Fig. 2 shows how the hollow bodies can be stacked or nested in one another; Figs. 3A and B show how the hollow bodies are filled and sealed; and Fig. 4 finally shows an illustration of the finished, bottle-like or tube¬ like packaging container. DESCRIPTION OF PREFERRED EMBODIMENT The apparatus for producing the bottle-like or tube-like packaging containers according to Fig. 1 consists of a forming cavity 1 shown in Fig. 1 A and whose cross sectional area progressively reduces from the aperture 2 of the forming cavity 1 to its innermost region. The walls 3 of the forming cavity 1 display holes or slots which can be placed in communication with a vacuum source, or at least be in communication with the ambient atmosphere. The production of the bottle or tube-like hollow body 4 is commenced in that a prefabricated cap 5 preferably of plastic material and similarly provided with through holes or slots is located in a per se known manner in the innermost region of the forming cavity 1 , whereafter it is possible, in the manner intimated, to dispose a conical bandolier 6 of, for instance, paper or plastic and provided with instructional or advertising text at a suitable place within the cavity 1 against its wall 3. In the next stage, a sheet 7 of thermoplastic material, for example polyethylene, polypropylene or similar polymer material, is applied over the open end of the cavity 1. The thus applied polymer sheet 7 may, on application, be heated or be subsequently heated to the plasticization temperature, whereafter it is fixedly retained by means of clamping devices 8 along the aperture 2 of the cavity 1. The above-disclosed polymer sheet 7 heated to plasticity is urged into the cavity 1 with the aid of a mandrel 9 whose mandrel rod displays flip- out or fold-out blades or vanes 10 which are so arranged that they are progressively folded out by degrees as the mandrel 9 is urged into the forming cavity 1 under expansion of the plastic polymer layer. In order to enable the plastic polymer material, under stretching and attenuation, to be applied against the walls 3 of the forming cavity 1 , it is necessary that the air between the stretched plastic material and the walls 3 of the forming cavity 1 can be evacuated and, to facilitate the forming operation, this space is placed in communication with a vacuum source, the plastic polymer material being, as a result of the pressure difference between its interior and exterior portions, brought into abutment against the inner walls 3 of the forming cavity 1. This forming may actively be facilitated at the same time as material thickness distribution can be controlled in that the blades or vanes 10 disposed on the mandrel 9 are folded out and assist in forcing the stretched plastic layer against the walls 3 of the cavity 1. If required, the forming effect may be further amplified and the process speeded-up by connecting that portion of the forming cavity 1 in which the movable mandrel 9 is located to a source of compressed air, the stretched plastic film being actively "blown" or urged against the walls 3 of the cavity 1. The folding out of the above-mentioned blades or vanes 10 continues progressively during insertion of the mandrel 9, and can be guided by a cam surface. The final position is achieved when the mandrel 9 with its forward portion 11 presses parts of the plastically deformed plastic material against the inside of the prefabricated cap 5 inserted in the innermost region of the cavity 1. In order that the portion of the plastic film inserted into the cap 5 accurately adheres to the inner region of the cap 5 (which preferably displays screw threads), the cap 5 should be provided with holes or slots and the outer region of the cap 5 should be connected to a vacuum source so that the warm and formable plastic film may be actively brought into contact against the inner region of the cap 5. The cap 5, which may preferably be a plastic cap produced in a suitable manner such as injection moulding, consists, in the embodiment described here, of a circular frontal plate from whose periphery departs an annular or tubular portion. The inner region of the above tubular or annular portion displays, for example, the above-mentioned screw threads, while the circular frontal portion displays a circular projecting, sharp edge. When the forward portion of the mandrel 9 urges parts of the stretched plastic film against the inside of the circular disk of the cap 5 in the region inside the above-mentioned projecting circular, per se closed edge, the above- mentioned portion of the plastic material can be sealed to the cap 5 in the region inside the sharp annular edge and be urged against the sharp edge so that the material is wholly or partly breached or weakened. The sealing of the stretched plastic layer in the region inside the annular edge against the inside of the cap 5 can be effected either with the aid of heat and pressure or with the aid of ultrasonic sound, the principle being that a good communication is established between the stretched plastic layer over the forward edge of the mandrel 9 and the inside of the cap 5, and that the stretched plastic film is, in the region outside the above-mentioned seal, effectively weakened or breached by means of the previously mentioned sharp edge. After the forming of the hollow body 4 by stretching of the polymer sheet 7 heated to plasticity, the hollow body 4 is withdrawn with the applied cap 5 out of the forming cavityΛhe mould 1 in which the hollow body 4 has been formed and, as is apparent from Fig. 2, a plurality of hollow bodies may be stacked or nested in one another for facilitating transport and handling. As is apparent from Fig. 3, the bottle-like packaging containers 4 are filled through their open bottom region 2 and, as is intimated in Fig. 3 B, this bottom opening 2 is closed and sealed with the aid of a prefabricated bottom plate 12 which, in a suitable manner such as by heat-sealing, is applied against the bottom edge line of the hollow body 4. The finished, bottle-like package 13 is shown in Fig. 4. On opening of the package 13 in connection with making available of the contents enclosed therein, the cap 5 is unscrewed, in which event a certain initial resistance is met at the start of the opening operation, since it is necessary on twisting of the cap 5 simultaneously to break off the portion of the plastic material drawn into the cap 5 and weakened by the annular sharp edge. This situation, that the cap 5 must initially be broken free in this manner, also constitutes a guarantee for the consumer that the package has not previously been opened. When the portion of the plastic film sealed against the inside of the cap 5 has been separated from the rest of the deep-drawn or vacuum-formed plastic portion, the cap 5 may be unscrewed and an opening hole or mouth is exposed through which the contents of the package may be dispensed. As was mentioned by way of introduction, the package may also be designed as a thin-walled tube which is preferably filled with viscous or pasty contents, for example mustard, caviar, tomato puree etc. Such a tube may traditionally be provided with a screw or snap closure of the prefabricated type, and the cap itself may advantageously be provided with a tipped tool which, after removal of the cap, may be employed for mechanically penetrating the packaging wall in the region of the seal proper. In this latter described case, the inner portion of the cap must not, thus, be welded together with the deep-drawn hollow body. It has proved that, using the method according to the present invention, it is possible in a rational and economical manner to produce bottle-like packaging containers which are provided with a reclosable opening. By employing the method according to the present invention, the package may be made very thin-walled and thereby cheap to produce. The present invention should not be considered as restricted to that described above and shown on the Drawings, many modifications being conceivable without departing from the spirit and scope of the appended Claims.

Claims: WHAT IS CLAIMED IS: 1. A method of producing bottle or tube-like, capped packaging containers (13) from a polymer material formable in the heated state, 5 characterized In that a prefabricated cap (5), preferably provided with interior threads and displaying through holes or slots, is disposed at the innermost region of a forming cavity (1), whose side walls (3), counting from the aperture (2) of the cavity (1) are of such design that progressively disposed cross-sections through the cavity (1) from its aperture (2) towards 1 0 its innermost region display reducing cross-sectional area; that a sheet (7) of a polymer material heated to plasticity and plastic deformability is applied over the aperture (2) of said cavity (1) and is fixedly retained around the aperture with the aid of clamping devices (8), whereafter said polymer sheet (7) is insertible, by means of a mandrel (9) displaying blades or vanes (10) I 5 radially movable out from the mandrel (9) which is urged into the forming cavity (1) while all of the wall portions (3) of the cavity (1) are, through holes or slots provided in the walls, placed in communication with a vacuum source so that the polymer sheet (7) inserted in the forming cavity (1) by stretching and plastic deformation under attenuation and surface 0 magnification, is caused, at least partly with the aid of said guided blades or vanes, to connect to the walls (3) of the forming cavity (1); and that the central portion of said plastic polymer sheet is displaced by the mandrel (9) up into and brought into contact with said cap (5) inserted in the forming cavity (1), the portions of the polymer material inserted into the cap (5) 5 being, with the aid of a vacuum, caused to connect against the inside of the cap (5). 2. The method as claimed in Claim 1, characterized in that said cap (5) displays a circular plate from whose periphery there departs an annular cylindrical portion whose inside is provided with screw threads; 0 and that the inside of the circular portion displays a projecting sharp edge which is in the form of a per se closed ring and which is symmetrically disposed with the cylindrical portion. 3. The method as claimed in Claim 1 , characterized in that said mandrel (9) with whose aid the polymer sheet (7) heated to plasticity is 35 inserted into said cavity (1) displays, along its forward portion, means for urging those parts of the polymer sheet which are in direct contact with said means against the inside of the circular plate of said cap (5) in the region defined by said projecting annular edge, whereupon that portion of the polymer material which has been pressed into said cap (5) against the inside of said circular plate is fixed against the inside of the cap (5) and is 5 wholly or partly penetrated or weakened along those parts which are urged against said annular edge. 4. The method as claimed in Claim 1 , characterized in that on positive insertion of said mandrel (9) into the cavity (1), blades or vanes (10) are pressed out in a direction from the mandrel (9) towards the inside of the I 0 cavity (1) said blades or vanes (10) being progressively caused to move from the operating rod of the mandrel (9) in order, when the mandrel (9) is wholly forced into the cavity (1), to have attained a position where parts of the plastic polymer material are urged against the walls of the cavity (1) with the aid of said blades or vanes (10). 1 5 5. Hollow bodies (4) produced in accordance with the method as claimed in claim 1 , characterized in that because of their progressively reducing cross-sectional area from the end (2) of the hollow bodies (4) and towards their interior, the hollow bodies may be telescopically stacked or nested in one another. 0 6. A packaging container (13) filled with contents and produced from a hollow body (4) as claimed in Claim 5, characterized in that after the filling operation, it is provided with a bottom (12) of plastic material which, by means of heat and pressure, is sealed against the opening zone of said filled hollow body (4). 25

Inventors: BRUHN KRISTER, BRUHN, KRISTER
Applicants: BRUHN KRISTER, TETRA LAVAL HOLDINGS & FINANCE, BRUHN, KRISTER, TETRA LAVAL HOLDINGS & FINANCE S.A.
Application year: 1994
Main classification: B29C51
IPC codes: B29C49, B29C51, B29L22